Ok so, if I double click the .iso icon, do I need to do anything else to install it on my hard disk, or will it "just work? lol And yes, of course it is legal. I am serious about that.

An ISO is a disk image. Think of it like inserting a real disc into your Superdrive. Double-clicking on it doesn't install anything, it simply mounts the disc. There may very well be an application on the disc that can be installed, but the simple act of mounting it doesn't install anything.

Liquid and computers don't mix. It might seem simple, but we see an incredible amount of people post here about spills. Keep drinks and other liquids away from your expensive electronics!